This invention relates to the continuous production of iron at the cathode of an electrode-position cell continuously fed from a holding or regeneration tank with electrolyte bearing ferrous ions. The predominant reaction occurring at the anode yields ferric ions which are carried away from the cell in the electrolyte returning to the holding tank. Besides holding, at any one instant, in the region of 90% of the total electrolyte volume, this tank is fed with metallic iron which serves to convert the ferric ions back to ferrous ions thereby reconstituting, i.e. regenerating, the electrolyte.
The electrolyte is preferably at an elevated temperature in order that the deposited iron is ductile. This is particularly important in the case where iron is continuously stripped from the cathode as foil; ductility is a desirable attribute or characteristic of a metal foil. This production of foil, which when stripped from the cathode displays sufficient ductility to render annealing unnecessary, requires an electrolyte temperature typically in the region of 95.degree. C. At such high electrolyte temperatures the rate of hydrolysis of ferric ions, in the pH region 0.3 to 1.4 which is that normally adopted for the electrodeposition of ductile iron foil, to form oxides of iron, termed sludge, is such that the sludge interferes with the smooth-running operation of the deposition apparatus. The problem is further compounded since for the production of foil on a commercially viable basis, passage of a very high current is required in the deposition cell. This in turn gives rise to a correspondingly large heating effect and consequently the temperature of electrolyte leaving the cell is appreciably higher than the temperature of electrolyte entering the cell.